Cat's Claw (Uncaria tomentosa) is a large climbing vine indigenous to the Amazon basin and other tropical areas of Central and South America. The bark and root have been used in traditional medicine by indigenous Amazonian peoples for at least 2,000 years to treat inflammation, infections, and gastrointestinal disorders. Today it is sold globally as a dietary supplement, most commonly standardized to its pentacyclic oxindole alkaloid (POA) content.

Cat's Claw exerts its effects primarily through inhibition of the pro-inflammatory transcription factor NF-κB, reducing downstream production of TNF-alpha, interleukin-1β, and other inflammatory cytokines. Its pentacyclic oxindole alkaloids (POAs) appear to stimulate immune cell activity, including enhancement of phagocytosis and T-lymphocyte function. The quinovic acid glycosides also contribute antioxidant activity, helping to neutralize reactive oxygen species involved in tissue damage.

Standardized extracts (capsules or tablets) provide the most consistent POA content and are the form used in most clinical studies, typically standardized to 1.3–3% POA content. Bark decoctions and teas are the traditional preparation but offer variable alkaloid concentrations. Tinctures provide intermediate bioavailability. Products explicitly labeled as TOA-free are often marketed for superior immunological effect, though direct comparative human trial data on this claim remain limited.

• Rheumatoid Arthritis
• Osteoarthritis
• Immune Support
• Inflammation

• Reduction of joint damage progression in early rheumatoid arthritis (preliminary evidence from Mur et al. 2002; not confirmed in long-term trials)

• Nausea (most commonly reported, particularly on empty stomach)
• Diarrhea or loose stools
• Abdominal cramping
• Dizziness (rare, possibly related to hypotensive alkaloid activity)
• Headache (rare)
• Potential hypotension at high doses
• Theoretical increased bleeding risk with antiplatelet constituents
• Rare reports of kidney damage at very high doses (case reports, not confirmed in controlled trials)

• Recommended daily: Standardized extract (standardized to POA content): 250–350 mg once or twice daily (500–700 mg/day total). Traditional bark decoction: 1–2 g of dried bark boiled in water for 15 minutes, 2–3 times daily. Rheumatoid arthritis trials used 60 mg/day of a specific POA-standardized extract; osteoarthritis trial used 100 mg/day of freeze-dried extract — dose should match the preparation's standardization.
• Best time of day: With meals to minimize GI side effects; no evidence favoring morning versus evening specifically
• With or without food: Take with food — reduces risk of nausea and GI discomfort, and may improve tolerability in sensitive individuals
• Time to effect: 4–8 weeks for joint pain and inflammation; some immune-related changes reported within 2–4 weeks
• How long to take it: Most clinical trials ran 4–24 weeks. For chronic conditions, use for 8–12 weeks then reassess with a healthcare provider. Cycling (e.g., 8 weeks on, 2–4 weeks off) is commonly recommended in traditional herbalism but lacks formal clinical evidence. Not recommended for continuous use beyond 6 months without medical supervision due to absence of long-term safety data.